economy. a plot on the new york stock exchange. >> these tools have helped us. >> reporter: the fbi said that intercepted e-mail from an al qaeda leader in yemen led to this man and two other americans. they were in the initial stages of planning their attack, seven years after 9/11. >> the fbi disrupted and arrested these individuals. >> reporter: the newly-declassifieied case is 1 50 terror plots that the fbi says could not be disrupted bout the nsa spying programs. the director defended the program against criticism that they violate americans' privacy. >> i would rather be here today debating this point, than try to explain how we failed to prevent another 9/11. >> reporter: civil liberties groups say the government has gone too far and many of the still classified plots could likely have been caught another way. >> the question is not simply whether plots were disrupted. but whether to disrupt those plots we need to engage in dragnet surveillance. >> reporter: top lawmakers disagree. >> t